Polar fluid removal from surfaces using supercritical fluids

Abstract

A method for removing polar fluids from the surface of a substrate using a supercritical fluid is described. Substrates that may be cleaned include microelectronic devices such as integrated circuits, micro-electro mechanical devices, and optoelectronic devices. The surfaces of these devices may include foamed polymers, such as those used as dielectric material. Supercritical fluids useful for removal of polar fluids generally include an oxygen-containing organic compound in the supercritical state. The removal of polar fluids using supercritical fluids may be supplemented by other cleaning methods using supercritical fluids to remove particulate matter from the surface of the substrate.

1 . A method of cleaning a surface of a substrate, comprising: 
 contacting the substrate with a solvation fluid comprising an oxygen-containing organic compound in a supercritical state; and    returning the oxygen-containing organic compound to a non-supercritical state to remove at least a portion of a polar fluid present on the surface of the substrate.    
   
   
       2 . The method of  claim 1 , wherein the surface comprises a porous material.  
   
   
       3 . The method of  claim 2 , wherein the porous material has a maximum cell size of at most about 0.3 microns.  
   
   
       4 . The method of  claim 1 , wherein the surface comprises a polymer layer.  
   
   
       5 . The method of  claim 4 , wherein the polymer layer comprises a foamed polymer.  
   
   
       6 . The method of  claim 1 , wherein the substrate is a microelectronic substrate.  
   
   
       7 . The method of  claim 1 , wherein the oxygen-containing organic compound is returned to a non-supercritical state by reducing its pressure.  
   
   
       8 . The method of  claim 1 , wherein the oxygen-containing organic compound is returned to a non-supercritical state by reducing its temperature.  
   
   
       9 . The method of  claim 1 , wherein the oxygen-containing organic compound comprises an alcohol or an ether.  
   
   
       10 . The method of  claim 1 , wherein the oxygen-containing organic compound comprises ethyl alcohol, methyl alcohol, or ethyl ether.  
   
   
       11 . The method of  claim 1 , wherein the oxygen-containing organic compound comprises ethyl alcohol.  
   
   
       12 . The method of  claim 1 , wherein the polar fluid comprises water.  
   
   
       13 . The method of  claim 1 , further comprising drying the surface of the substrate after returning the oxygen-containing organic compound to a non-supercritical state.  
   
   
       14 . The method of  claim 1 , further comprising delivering sonic wave energy to the substrate.  
   
   
       15 . A method of cleaning a porous surface of a microelectronic substrate, comprising: 
 contacting the microelectronic substrate with a solvation fluid comprising an oxygen-containing organic compound in a supercritical state; and    returning the oxygen-containing organic compound to a non-supercritical state to remove at least a portion of a polar fluid present on the porous surface of the microelectronic substrate.    
   
   
       16 . The method of  claim 15 , wherein the oxygen-containing organic compound comprises ethyl alcohol, methyl alcohol, or ethyl ether.  
   
   
       17 . A method of cleaning a surface of a substrate, comprising: 
 placing the substrate in contact with a stripping fluid;    contacting the substrate or stripping fluid with cleaning fluid in a supercritical state;    returning the cleaning fluid to a non-supercritical state to remove at least a portion of a waste material present on the surface of the substrate;    contacting the substrate with a solvation fluid comprising an oxygen-containing organic compound in a supercritical state; and    returning the oxygen-containing organic compound to a non-supercritical state to remove at least a portion of a polar fluid present on the surface of the substrate.    
   
   
       18 . The method of  claim 17 , wherein the cleaning fluid comprises carbon dioxide, ethane, ethylene, nitrous oxide, propane, or xenon.  
   
   
       19 . The method of  claim 17 , wherein the stripping fluid comprises sulfuric acid solution, hydrogen peroxide solution, or de-ionized water.  
   
   
       20 . The method of  claim 17 , wherein the substrate is dried before contacting the substrate with a solvation fluid.  
   
   
       21 . The method of  claim 17 , wherein the surface comprises a porous material.  
   
   
       22 . The method of  claim 21 , wherein the porous material has a maximum cell size of at most about 0.3 microns.  
   
   
       23 . The method of  claim 17 , wherein the surface comprises a polymer layer.  
   
   
       24 . The method of  claim 23 , wherein the polymer layer comprises a foamed polymer.  
   
   
       25 . The method of  claim 17 , wherein the substrate is a microelectronic substrate.  
   
   
       26 . The method of  claim 17 , wherein the oxygen-containing organic compound is returned to a non-supercritical state by reducing its pressure.  
   
   
       27 . The method of  claim 17 , wherein the oxygen-containing organic compound is returned to a non-supercritical state by reducing its temperature.  
   
   
       28 . The method of  claim 17 , wherein the oxygen-containing organic compound comprises an alcohol or an ether.  
   
   
       29 . The method of  claim 17 , wherein the oxygen-containing organic compound comprises ethyl alcohol, methyl alcohol, or ethyl ether.  
   
   
       30 . The method of  claim 17 , wherein the oxygen-containing organic compound comprises ethyl alcohol.  
   
   
       31 . The method of  claim 17 , wherein the polar fluid comprises water.  
   
   
       32 . The method of  claim 17 , further comprising delivering sonic wave energy to the substrate.  
   
   
       33 . A method of cleaning a porous surface of a microelectronic substrate, comprising: 
 placing the microelectronic substrate in contact with a stripping fluid;    contacting the substrate or the stripping fluid with cleaning fluid in a supercritical state;    returning the cleaning fluid to a non-supercritical state to remove at least a portion of a waste material present on the porous surface of the microelectronic substrate;    drying the microelectronic substrate;    contacting the microelectronic substrate with a solvation fluid comprising an oxygen-containing organic compound in a supercritical state; and    returning the oxygen-containing organic compound to a non-supercritical state to remove at least a portion of a polar fluid present on the porous surface of the microelectronic substrate.    
   
   
       34 . The method of  claim 33 , wherein the cleaning fluid comprises carbon dioxide, ethane, ethylene, ethylene, nitrous oxide, propane, or xenon.  
   
   
       35 . The method of  claim 33 , wherein the stripping fluid comprises sulfuric acid solution, hydrogen peroxide solution, or de-ionized water.  
   
   
       36 . A method of cleaning a surface of a substrate, comprising: 
 contacting the substrate with a gaseous plasma;    contacting the substrate with cleaning fluid in a supercritical state;    returning the cleaning fluid to a non-supercritical state to remove at least a portion of a waste material present on the surface of the substrate;    contacting the substrate with a solvation fluid comprising an oxygen-containing organic compound in a supercritical state; and    returning the oxygen-containing organic compound to a non-supercritical state to remove at least a portion of a polar fluid present on the surface of the substrate.    
   
   
       37 . The method of  claim 36 , wherein the gaseous plasma comprises an oxidizer selected from the group consisting of SO 2 , N 2 O, NO, NO 2 , O 3 , H 2 O 2 , F 2 , Cl 2 , Br 2 , and O 2 .  
   
   
       38 . The method of  claim 36 , wherein the surface comprises a porous material.  
   
   
       39 . The method of  claim 38 , wherein the porous material has a maximum cell size of at most about 0.3 microns.  
   
   
       40 . The method of  claim 36 , wherein the surface comprises a polymer layer.  
   
   
       41 . The method of  claim 40 , wherein the polymer layer comprises a foamed polymer.  
   
   
       42 . The method of  claim 36 , wherein the substrate is a microelectronic substrate.  
   
   
       43 . The method of  claim 36 , wherein the oxygen-containing organic compound is returned to a non-supercritical state by reducing its pressure.  
   
   
       44 . The method of  claim 36 , wherein the oxygen-containing organic compound is returned to a non-supercritical state by reducing its temperature.  
   
   
       45 . The method of  claim 36 , wherein the oxygen-containing organic compound comprises an alcohol or an ether.  
   
   
       46 . The method of  claim 36 , wherein the oxygen-containing organic compound comprises ethyl alcohol, methyl alcohol, or ethyl ether.  
   
   
       47 . The method of  claim 36 , wherein the oxygen-containing organic compound comprises ethyl alcohol.  
   
   
       48 . The method of  claim 36 , wherein the polar fluid comprises water.  
   
   
       49 . The method of  claim 36 , further comprising delivering sonic wave energy to the substrate.  
   
   
       50 . A method of cleaning a porous surface of a microelectronic substrate, comprising: 
 contacting the microelectronic substrate with a gaseous plasma;    contacting the microelectronic substrate with cleaning fluid in a supercritical state;    returning the cleaning fluid to a non-supercritical state to remove at least a portion of a waste material present on the porous surface of the microelectronic substrate;    contacting the microelectronic substrate with a solvation fluid comprising an oxygen-containing organic compound in a supercritical state; and    returning the oxygen-containing organic compound to a non-supercritical state to remove at least a portion of a polar fluid present on the polar surface of the microelectronic substrate.    
   
   
       51 . The method of  claim 50 , wherein the gaseous plasma comprises an oxidizer selected from the group consisting of SO 2 , N 2 O, NO, NO 2 , O 3 , H 2 O 2 , F 2 , Cl 2 , Br 2 , and O 2 .  
   
   
       52 . A composition comprising a microelectronic substrate or microelectronic substrate assembly in contact with a solvation fluid comprising an oxygen-containing organic compound in a supercritical state.  
   
   
       53 . The composition of  claim 52 , wherein the oxygen-containing organic compound comprises an alcohol or an ether.  
   
   
       54 . The composition of  claim 52 , wherein the oxygen-containing organic compound comprises ethyl alcohol, methyl alcohol, or ethyl ether.  
   
   
       55 . The composition of  claim 52 , wherein the oxygen-containing organic compound comprises ethyl alcohol.  
   
   
       56 . The composition of  claim 52 , wherein the microelectronic substrate comprises a foamed polymer.  
   
   
       57 . The composition of  claim 56 , wherein the foamed polymer has a maximum cell size of at most about 0.3 microns.